Polyethylene Wear Particle Analysis of THA

Research method In this study, the investigators conducted the following steps to determine the in vivo wear particles (number, size, and morphology) of conventional polyethylene, whose long-term results have already been clarified, and vitamin E-containing polyethylene, whose mid- to long-term results have not yet been clarified. Clarifying the difference.

Target of this research In this study, the investigators will focus on patients undergoing revision hip arthroplasty as a routine medical treatment.

First total joint replacement

• 30 patients using polyethylene containing Vitamin E
• 30 patients using conventional polyethylene (no high cross-linking)
• 30 patients using conventional polyethylene (with high cross-linking)

Accumulation of periarticular tissue In this study, the investigators will focus on patients undergoing revision hip arthroplasty as a routine medical treatment.

The test will be conducted after obtaining approval from the ethics committee at each facility and obtaining informed consent. The pericapsular tissue, which is removed during surgery and usually discarded, is obtained and fixed in formalin fixative. The tissue will be transported to the Department of Orthopedic Surgery, Osaka Public University Graduate School of Medicine for analysis. International transportation of tissues requires outsourcing to specialized companies with experience in transporting tissues from overseas.

Isolation of polyethylene wear debris The collected tissue around the joint capsule is immersed in 5Mol sodium hydroxide at 65°C for 1 hour to decompose the protein. Make a sucrose layer (5, 10, 20%) in a 14ml tube (14PA tube, Hitachi Koki Co, Ltd, Tokyo, Japan), add the dissolved solution, and place in an ultracentrifuge (CP100a, P28S1014 rotor, Hitachi Koki). Ultracentrifuge at 28,000 rpm [103,7009g] for 3 hours at 4°C. Prepare an isopropanol layer (0.90 and 0.96 g/mL) in a 40 ml tube (40PA tube, Hitachi Koki Co, Ltd, Tokyo, Japan), add the upper layer of sucrose layer, and centrifuge at 28,000 rpm (103,7009 g) and perform ultracentrifugation at 4°C for 1 hour. The isopropanol interlayer is collected to isolate polyethylene wear debris.

Analysis of polyethylene wear debris The isopropanol interlayer is filtered through a 0.1 μm polycarbonate filter (VCTP 013-00, Millipore Corporation, Bedford, MA). Dry the polycarbonate filter, fix it on an aluminum pedestal (M4, Nisshin EM Co, Ltd, Tokyo, Japan), and apply platinum coating (E-1030 ion sputter, Hitachi Science Systems Ltd, Tokyo, Japan). Observe the polyethylene wear particles on the polycarbonate filter using a scanning electron microscope (S4700SI, Hitachi Ltd, Tokyo, Japan), and analyze the following items using an image analyzer (Mac Scope, Mitani Co, Tokyo, Japan).

• Number of polyethylene wear particles (number per 1g of tissue)
• Size (Equivalent circle diameter [μm])
• Shape (aspect ratio, roundness)

Comparison of iv vivo polyethylene wear powder morphology depending on polyethylene material The number, size, and form of polyethylene wear debris will be compared between conventional polyethylene, whose long-term results have already been clarified, and vitamin E-containing polyethylene, whose medium- to long-term results have not yet been clarified. The investigators also investigated factors that affect polyethylene wear in vivo (age, height, weight, period from initial surgery to revision surgery, hip joint range of motion, hip prosthesis clinical score [Hip dysfunction and Osteoarthritis Outcome Score for Joint Replacement [HOOS Jr], Harris Hip Score, University of California Los Angeles [UCLA] activity score]).

Inclusion criteria

• Patients undergoing revision hip arthroplasty within the study period
• Patients over 20 years old
• Patients who have received a sufficient explanation, have sufficient understanding, and have given their free written consent.
• Patients who have passed 2 years or more since their first total hip arthroplasty

Exclusion criteria

• Patients who are judged to be unsuitable as research subjects by the research physician